1. Field of the Invention
This invention relates to a semiconductor device such as a switch, variable capacitor, acceleration sensor, gyroscope, inertia sensor chip and XY stage using a piezoelectric actuator formed by use of a micromachine or micro electro mechanical systems (MEMS) technique.
2. Description of the Related Art
In a driving system of an actuator formed by use of the MEMS technique, electrostatic-, piezoelectric-, thermal- and electromagnetic-type driving systems are provided. The piezoelectric-type driving system among the above systems can perform a driving operation at low voltage with low power consumption, and is suitable for the driving system of an actuator mounted on a mobile telephone. The piezoelectric actuator is used in a switch or variable capacitor, for example.
The switch or variable capacitor used in the piezoelectric actuator is described in, for example, H. C. Lee et al, “Silicon Bulk Micromachined RF MEMS Switches with 3.5 Volts Operation by using Piezoelectric Actuator”, MTT-S Digest, pp 585-588, 2004. If the piezoelectric actuator is used as is described in the above paper, a displacement of several microns can be caused to occur in the upper or lower direction by use of a low voltage of approximately 3 V.
However, since the conventional piezoelectric actuator cannot produce large displacement in the lateral direction, applicable devices are limited.